The subject matter disclosed herein relates to a device and method of verifying electrical pulses, and in particular to a device and method for verifying electrical utility meter pulses in parallel with a load monitoring system.
Many applications use pulse generators to transmit a pulse signal that indicates a unit of measurement. In an exemplary application, an electrical utility meter uses a relay to generate a pulse each time a dial on the utility meter rotates. By accumulating the number of pulses transmitted during a given time period, a usage parameter (e.g. kilowatt-hours) may be determined. The use of a pulse generator provides advantages in extending older technologies that may lack communications capability. The pulse generator further provides advantages by allowing a third party access to information from a metering device without having to provide a connection to the processing or communication circuitry of the meter. It should be appreciated that providing access to the communication circuitry of a meter may weaken security or create the risk of unauthorized access.
In an exemplary embodiment of an electrical utility meter, the pulse generator may be relay having two dry contacts (form C) or a single dry contact (form A), sometimes referred to as a KYZ or KY, KZ pulse output relay. Each time the meter disk or disk emulator (on digital meters) rotates a full turn, the relay changes state between the dry contacts. This change in state creates what can be considered a pulse signal on the relay output. By knowing the scaling of the disk rotation, the amount of electrical power consumed may be determined by counting the number of pulses generated over a period of time. The relay output for electrical meters is often used to provide the customer with a way to monitor their electrical usage in near real-time. It is common for electrical meters to have the pulse generating relay built in and connected with an external terminal block or wiring harness that allows the customer access to the pulses.
Another application is in energy usage consulting. Devices are commercially available that connect to the front of a utility meter and optically determine the rotation of the meter disk (on mechanical meters) or disk emulator/calibration pulses (on digital meters). The device then generates a pulse each time that a disk or disk emulator/calibration pulses completes a rotation. The energy consultant may then use this information to determine the impact of various changes that are made to the connected facility rather than waiting for the monthly utility account statement.
One problem that arises in these applications is when there is a discrepancy between the meter and the system that accumulates the pulses. It is difficult to trace the source of the error to determine if the error originates in the utility meter, or in the customer system.
Accordingly, while existing pulse systems are suitable for their intended purpose, there remains a need for improvements particularly in systems and methods for verifying the accuracy of the pulse system.